For some reason, Chains of Satinav was really sluggish, especially during close-ups in dialogue. So I tried to run it in windowed mode and see if it helps. Unfortunately, it caused the game to crash at start-up. The menu screen shows, but immediately after, the game crashes. The problem persists after I turned full screen back on and re-installed it.

Looks like removing all game data and reinstalling did work. Shame that it can't be made to run faster, though.